Archive of the former Yahoo!Groups mailing list: Discussion about the Korg PolySix synthesizer

A while ago I was given - to clean and repair - a pair of Polysixes that belonged to a
friend. I managed to get the keyboards cleaned and working perfectly, one has a green
battery, the other has a blue one, and one of them (it varies which one as I keep moving
the chip) has a faulty 2056 chip.

Originally both had bad keyboards, one had a stuck voice, and that was the size of it. I
repaired both keyboards, identified the faulty voice, and brought the cleaner of the two
down to the studio to play with. It developed a new fault:

When powered up, half the LEDs on the patchbank light up, not all of them.
Selecting patches is unpredictable within a fixed pattern - 2 can be selected, but doesn't
light the LED.
Tape Enable doesn't work. The LFO cranks up, but nothing else happens.
Switching the Sub Oscillator doesn't work correctly.

I swapped the 371 etc. boards over in the hope that it might be that, and of course, put
the working filter chip in the other keyboard. I think the fault must lie within the 367A
board, but the battery (blue) doesn't appear to have leaked.

The other one appears to be working normally, but I'm holding off putting the screws in
until I can confirm a couple of things:

First - the green battery. From what I've read these don't suffer the same leaking and
some places imply green ones are NiMH. Is that the case?
Second - when first started, the Polysix 'rises' in pitch until it is in tune. It's just the first
note/s player - basically it stabilises. I haven't read of this behaviour anywhere so I'm
assuming something is failing.

Patch storage works, and I have loaded/saved to tape with it. Since all the keys work and
this works, once I can find out if the pitch rise behaviour is normal/fixable, and the battery
can be trusted, I can put the synth back together and return it.

But the first keyboard; it was working fine then developed this issue without any visible
signs - all socketed chips are seated (I have removed and cleaned connections with no
noticeable changes), the voice chips all work aside from the broken one, and the button
board works in the other synth just fine (and the one in the other synth, which works, was
originally in this one).

I expect a course of replacing electrolytics might help the working one a bit, but the
broken one sounds more complex.

Best Wishes,
Richard